Variables exercise - Free Printable

To solve this worksheet, we need to break down each scenario into three parts:

1. Independent Variable (I): The thing that is changed on purpose or the "cause." It's what you control.
2. Dependent Variable (D): The result or the "effect." It's what you measure to see if it changed because of the independent variable.
3. Constant (C): Things that stay the same throughout the experiment to make sure the test is fair.

Let’s go through each question step-by-step.

Question 1: *A study was done to find if different tire treads affect the braking distance of a car.*
* Analysis: We are changing the tires to see what happens to the stopping distance.
* I: Tire treads (This is what is being tested).
* D: Braking distance (This is what is measured).
* C: Car model, speed before braking, road surface, driver reaction time.

Question 2: *The time it takes to run a mile depends on the person’s running speed.*
* Analysis: If a person runs faster or slower, how does that change their finish time?
* I: Running speed (This is the cause).
* D: Time to run a mile (This is the effect/result).
* C: Distance (1 mile), weather conditions, terrain.

Question 3: *The height of bean plants depends on the amount of water they receive.*
* Analysis: We give plants different amounts of water and watch them grow.
* I: Amount of water (This is what changes).
* D: Height of bean plants (This is what grows/changes).
* C: Type of plant, sunlight, soil type, pot size.

Question 4: *The higher the temperature of the air in the oven, the faster a cake will bake.*
* Analysis: Changing the heat changes how quickly the cake is done.
* I: Temperature of the air in the oven.
* D: Baking time (or "how fast the cake bakes").
* C: Recipe, ingredients, pan size, starting temperature of batter.

Question 5: *Lemon trees receiving the most water produced the most lemons.*
* Analysis: Giving more water leads to more fruit.
* I: Amount of water received.
* D: Number of lemons produced.
* C: Tree species, age of tree, soil, sunlight exposure.

Question 6: *An investigation found that more bushels of potatoes were produced when the soil was fertilized more.*
* Analysis: Adding fertilizer affects the potato harvest.
* I: Amount of fertilizer used.
* D: Potato production (bushels).
* C: Soil type, potato variety, amount of water/rainfall.

Question 7: *Students measured the temperature of the water at different depths in Lake Skywalker and found that the temperature varied.*
* Analysis: They went deeper into the lake to check the temp.
* I: Depth of the water (This is the location chosen by the students).
* D: Water temperature (This is what was measured).
* C: Time of day, specific body of water (Lake Skywalker), thermometer used.

Question 8: *The amount of pollution produced by cars was measured for cars using gasoline containing different amounts of lead.*
* Analysis: Testing fuel types to see pollution levels.
* I: Amount of lead in gasoline.
* D: Amount of pollution produced.
* C: Car model, engine condition, driving distance/speed.

Question 9: *Four groups of rats are first massed and then fed identical diets except for the amount of vitamin A they receive... After 3 weeks... masses are measured again...*
* Analysis: The diet is mostly the same, but Vitamin A varies. The goal is to see if mass changes.
* I: Amount of Vitamin A.
* D: Mass of the rats (Change in mass).
* C: Diet (other than Vit A), cage environment, duration (3 weeks), breed of rat.

Final Answer:

1. I: Tire treads | D: Braking distance | C: Car, speed, road
2. I: Running speed | D: Time to run a mile | C: Distance (1 mile)
3. I: Amount of water | D: Height of bean plants | C: Sunlight, soil, plant type
4. I: Oven temperature | D: Baking time | C: Cake recipe, pan size
5. I: Amount of water | D: Number of lemons | C: Tree type, sunlight
6. I: Amount of fertilizer | D: Bushels of potatoes | C: Soil type, potato variety
7. I: Depth of water | D: Water temperature | C: Location (Lake Skywalker), time of day
8. I: Amount of lead in gasoline | D: Amount of pollution | C: Car type, driving distance
9. I: Amount of Vitamin A | D: Mass of the rats | C: Diet (rest of food), environment, duration